Sure the forger could have used a typewriter. Then all he/she had to do was forge Killians signature. It still wouldn't have passed careful scrutiny.
The person or persons who passed these fakes to CBS either knew they were forged, or not. The forger certainly knew they were forged, and he ain't talking. CBS gets off the hook because they can claim stupidity or incompetence, or both (and by continuing to stand by these forgeries, one might be inclined to believe that could be the case).
So unless someone starts to talk, or you somehow pin point the forger, this thing ends with a black eye on CBS (funny how their logo resembles a shiner anyway) and a lot of speculation on who did it.
But if speculation is all we end up with, then we can at least make a reasonable assumption that it wasn't the Russians (or Carl Rove, as Terry McAulliffe hinted).
Since Rove or the Russians ain't on the list, that leaves those who would like to see John Kerry elected. So, that's where we look.
I think some of the other posts here are very close to the truth, but we may never know who did it for sure. This does look like Lehane's modus operandi, and I didn't even know who he was until last night. With very little effort, I was convinced that not only would he be quite capable of this, but that he has a movtive.
I think he would like to be back in the Whitehouse.